Flexible device for transfixing and joining tissue

ABSTRACT

A surgical device is provided for use in joining a first tissue layer forming a first hollow region and a second tissue layer forming a wall of a second hollow region, to produce an anastomosis. The device comprises a needle capable of passing from the first region to the second region by penetrating the tissue layers, a tag removably carried by the needle, the tag having a trailing portion, and means for separating the tag from the needle after the needle has penetrated both layers, to leave the tag in the second hollow region, but with the trailing portion extending into the first hollow region. Anastomosis forming articles are described which comprise a pair of components for compressing the tissue layers between them.

The present patent application is a non-provisional application ofInternational Application No. PCT/GB02/01268, filed May 20, 2002.

FIELD OF THE INVENTION

This invention relates to methods and devices for transfixing andjoining tissues and, more particularly, to forming anastomoses.

BACKGROUND OF THE INVENTION

In abdominal and vascular surgery anastomosis, the joining together ofhollow structures, is an important goal. The ability to establishcontinuity between two hollow structures can relieve blockage due tocancer, inflammation or other pathology, can allow the removal ofabnormal tissue or organs, and, by bypassing a blocked segment, canallow the unimpeded movement of food or facilitate the flow of blood orbile through the body.

Anastomoses are most commonly formed at open abdominal surgery(laparotomy). Hand sewn anastomoses, usually in two or even threelayers, are widely performed but are time consuming and require largeincisions for hand access. Stapled anastomoses became widely performedespecially in colonic surgery since they allowed surgeons to remove lowrectal tumours. The short rectal remnant could be joined to the colonabove the tumour at a site where it was difficult to place stitches byhand, and in consequence allowed patients to recover without needing apermanent colostomy. The advent of laparoscopic surgery staplers allowedanastomoses to be formed through incisions of 1-2 cm or so that werejust large enough to allow passage of these instruments inside theabdominal or thoracic cavity.

Some aids to form anastomoses have been developed. J. B. Murphy, anAmerican surgeon working in Chicago in the 1880's, popularized surgicalanastomoses by creating a compression button device for anastomosis. Thedevice had two mushroom-shaped buttons, which could be placed in the twoorgans to be joined. The buttons could be pressed together by aninternal spring in the stalk of the mushroom and the organs would bewelded together by the consequent ischaemia (lack of blood supply) atthe sites where the buttons were pressed together. Eventually the buttondevice would fall through into the gut, leaving an anastomosis or holeand be passed through the body into the toilet. Compression buttonanastomoses are still used at open colonic surgery. The use of magnetsto compress tissue to form an anastomosis has also been described, and aspring compression button method using a biofragmentable ring has beenemployed, especially in the rectum.

An anastomosis procedure has been described in an article entitled“Anastomosis at Flexible Endoscopy: an experimental study of compressionbutton gastrojejunoscopy”, P Swain and N Mills, GastrointestinalEndoscopy 1991, 37: 625-631, in which, as its title implies, a method isdescribed of forming anastomoses using a flexible endoscope. The methoddescribed there involved introducing a flexible endoscope into one ofthe two structures to be joined (in this case the stomach), and enteringthe second of the two structures (in this case the small bowel) byforming an incision in the abdomen of the subject. The present inventionis directed, in one aspect thereof, to the formation of anastomoseswithout the need to make such external incisions, though in otheraspects thereof the means described herein which make this possible areapplied to anastomoses in the formation of which such incisions aremade.

The ability to form anastomoses using flexible endoscopic orpercutaneous procedures without opening the abdomen or chest or usinglaparoscopic methods might offer advantages especially to patients withadvanced cancer or in elderly or sick patients, who might withstandconventional surgery poorly. In particular, flexible endoscopy mightallow anastomoses to be formed from stomach to small bowel, duodenum togallbladder, and small bowel to colon.

Flexible endoscopy allows access to many hollow organs includingoesophagus, stomach, duodenum, small intestine and colon, and mostflexible endoscopes have a channel through which instruments can bepassed. Although the flexible endoscopes employed for most conventionalpurposes do not provide information on the location of tubularstructures outside the organ, modified flexible endoscopes employingultrasound are available which do. Endoscopic ultrasound is a hybridmethod, which uses ultrasound imaging at the tip of the endoscope butretains the optical imaging and internal instrument channel of aconventional endoscope. Some such endoscopes have their imaging arrayconstructed in a linear fashion, which allows good ultrasoundvisualization of organs adjacent to the organ in which the tip of theendoscope lies.

SUMMARY OF THE INVENTION

Devices are described here which can form anastomoses either throughflexible endoscopes or at percutaneous needle access, which do notrequire surgical incision or laparoscopy (although they might be usedduring either of these surgical methods to form an anastomosis), andwhich may be used in combination with ultrasound or x-ray imagingexternally to the patient or, preferably, imaging internally to thepatient, for example using endoscopic ultrasound.

Accordingly to the present invention there is provided a surgical devicefor use in joining a first tissue layer forming a wall of a first hollowregion and a second tissue layer forming a wall of a second hollowregion, the device comprising a needle capable of passing from the firstregion to the second region by penetrating the said tissue layers, a tagremovably carried by the needle, the tag having a trailing portion, andthe tag being separable from the needle after the needle has penetratedboth layers, to leave the tag in the second region, but with the saidtrailing portion extending into the first region. The trailing portionis preferably a thread or wire, with the tag being free to tilt withrespect thereto, after the tag has entered the second region.

The invention further provides a method of surgery which may employ theabove surgical device. In further aspects thereof the inventionadditionally provides various entities which may be used in carrying outthe surgical method, some of which may be capable of use in surgery notemploying the above mentioned tag. Also, it is within the scope of theinvention to use some of the ideas disclosed herein outside the field ofanastomosis formation.

According to another aspect of the present invention there is providedan element of a device for forming an anastomosis, which elementcomprises a hollow sheath, and an elongate carrier member passingthrough the hollow sheath, with a portion of the sheath being attachedto the carrier member and the remainder of the sheath being free to movelengthwise with respect to the carrier member, whereby such lengthwisemovement causes the sheath to bulge outwardly. Preferably the sheath isa braided sheath, and more preferably it is a braided sheath of asurgically acceptable metal. The portion of the sheath which is attachedto the carrier member is preferably at or adjacent one end thereof, andthe sheath preferably has a sliding collar at or adjacent its other endto assist the above mentioned lengthwise movement. This aspect of theinvention further provides a device for forming an anastomosis whichcomprises an element as set out above and a further element in the formof a cup for cooperating with the first mentioned element. The cuppreferably has an aperture therein for the carrier member to passthrough.

In a preferred form, the invention, in its various aspects, relates tothe formation of anastomoses.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail below with reference, to theaccompanying diagrammatic drawings, in which:

FIG. 1 shows the disposition of the hollow structures which are to bejoined by an anastomosis, and the apparatus components for doing so, atthe point in time when formation of the anastomosis is about to begin;

FIGS. 1 a and 1 b are a vertical section and a plan view, respectively,of part of the apparatus of FIG. 1;

FIG. 2 is a view corresponding to FIG. 1 but taken at a later point intime;

FIGS. 3 a and 3 b show two stages in the use of a device for holding thetwo tubular structures together prior to the formation of ananastomosis;

FIGS. 4 a to 4 e show successive stages in forming an anastomosis using,as one apparatus component, the device shown in FIGS. 3 a and 3 b, andFIG. 4 e is a cross sectional view through a bell-shaped button whichconstitutes another of the components used in FIGS. 4 a to 4 d;

FIGS. 5 a and 5 b show a modification of the loop-forming deviceemployed in FIGS. 3 a and 3 b and in FIGS. 4 a to 4 d;

FIG. 6 shows an alternative device to that illustrated in the earlierfigures, for forming an anastomosis;

FIGS. 7 a and 7 b show successive stages in the use of a releasemechanism which may be incorporated in some of the previouslyillustrated embodiments;

FIG. 8 is a diagram of part of the gastrointestinal tract to assist inunderstanding the anatomical aspects of what is described below;

FIG. 9 shows a button device for forming an anastomosis;

FIG. 10 shows a modified form of tag for use in the invention;

FIG. 11 shows an anastomosis forming device using a braided sheath; and

FIG. 12 shows a modification of part of the device of FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

Turning first to FIG. 8 of the drawings, it will be seen that this showspart of the gastrointestinal tract, and illustrates a tumour in theupper portion of the small bowel and the site at which it is desired toform an anastomosis to bypass the section of small bowel containing thetumour and thus permit its removal. What will now be described is theuse of the embodiment shown in FIGS. 1, 1 a, 1 b and 2, in conjunctionwith some known pieces of surgical equipment, to form the anastomosis.

Although there are a number of alternative ways in which the surgicalprocedure can be carried out, one of them involves the following steps.Firstly a conventional flexible endoscope is passed through the mouth ofthe patient and thence through the patient's stomach and out through thepylorus into the small bowel. The leading end of the endoscope is passedat least as far as the site of the tumour. If the tumour is small enoughit may be possible for the leading end of the endoscope to pass thetumour and reach the site for the anastomosis. If not, the leading endof the endoscope will stop at the tumour, but will need to have theoutlet of the relevant channel (for which see below) opposite the gapbetween the tumour and the opposing small bowel wall. A guide wire isthen passed down the biopsy channel of the endoscope until the leadingend of the guide wire is located at or adjacent the anastomosis site. Atthis point there are two alternative possibilities for the next step.One is to remove the endoscope from the patient, leaving the guide wireintact, and thereafter run a balloon catheter down the guide wire untilthe balloon is at or adjacent the anastomosis site. The alternative isto run the balloon catheter down the guide wire while the guide wire isstill in the biopsy channel of the endoscope. In either event, it may bedesirable for the balloon catheter to be one which is capable oftransmitting torque along its length (such catheters are known for usein cardiology), so as to assist in the passage of the balloon to thedesired site. The balloon of the balloon catheter can be inflated at anyconvenient stage during the forgoing procedure steps, or can be inflatedafter the step to be described immediately below, namely introducing aflexible ultrasound endoscope. The balloon is preferably in the shape ofa cylinder with rounded ends (a sausage shape), to facilitate its beingpassed to the intended site.

As just indicated, an ultrasound endoscope is introduced into thepatient, passing through the patient's mouth and thence into thestomach. The leading end of the ultrasound endoscope, instead of beingallowed to exit the stomach through the pylorus, is directed to thestomach side of the site for the anastomosis. The situation at theanastomosis site is now substantially as shown in FIG. 1 of the drawingsexcept that, contrary to what is shown in that figure, the leading endof a needle with which the ultrasound endoscope is provided is in aretracted position rather than a forward position.

Turning then to FIG. 1 in more detail, this shows a stomach wall portion1 and a portion 2 of the small bowel. An anastomosis is to be formedbetween the portions 1 and 2. Positioned adjacent the stomach wallportion 1 is the distal end of a flexible ultrasound endoscope 3 whichhas a biopsy channel 4. A hollow needle 5 is shown extending from theoutlet of the biopsy channel. The endoscope is provided, in knownmanner, with forward viewing optics adjacent the outlet of the biopsychannel, for viewing the area in front of the biopsy channel. FIGS. 1 aand 1 b show details of the tip portion of the hollow needle 5. As shownthere, it has a bevelled leading portion 5 a, terminating in a sharppoint 5 b. The interior of the needle (which is basically in the form ofa hollow cylinder) communicates with the exterior via a forward opening6 and a longitudinal slot 6 a which communicates with the forwardopening 6. The needle is longitudinally movable with respect to a sheath7, and the sheath is itself movable along the biopsy channel of theendoscope 3. A pusher 8 is longitudinally movable within the hollowinterior of the needle, and the purpose of the pusher is describedfurther below.

At its extreme distal end the endoscope carries an ultrasonic detector10, which preferably has a so-called linear detector array 11. Thisdetector array gives a field of view which is indicated by the brokenlines 12 in FIG. 1. In order to improve the image produced by theultrasonic detector 10 it may be surrounded by a balloon, indicated by abroken line 13, with the balloon being filled with water or otherliquid. However, this may not be necessary if the user of the endoscopeis able to gain sufficiently good contact directly between theultrasonic detector 10 and the stomach wall portion 1.

Within the small bowel is a balloon catheter, as mentioned above, theballoon being denoted by reference numeral 16 and the catheter itself byreference numeral 15. The guide wire along with the balloon catheter hasbeen introduced is denoted by reference numeral 17. Optionally, theexterior surface of the balloon may be covered with a reticulated sheath22 (shown in FIG. 2 but not in FIG. 1), or some other material withsimilar relevant properties, for a purpose which is further describedbelow. To assist in locating the tip of the endoscope 3 and the balloon16 immediately opposite one another at the anastomosis site, thecatheter may be provided with a further channel, in addition to thatused for inflating the balloon, through which a medium such as aeratedwater may be introduced, which is readily detected by an ultrasonicdetector.

As shown in FIGS. 1 a and 1 b a tag 20 is initially positioned adjacentthe distal end of the hollow interior of the needle 5. The tag may bemade for example, of a surgically acceptable metal. The tag has a thread21 extending to the exterior of the hollow channel and thence along apath which lies outside the endoscope but is approximately parallelthereto, and so out of the mouth of the patient. In an alternativeembodiment (not illustrated) the thread may pass through a channel ofthe endoscope itself.

When it is desired to commence formation of the anastomosis, the hollowneedle 5 is pushed through the stomach wall portion 1, and thencethrough the adjacent small bowel portion 2, so that it enters theballoon 16. When the needle enters the balloon it will permit the fluidtherein to escape, and the balloon will deflate at least gradually. Oneway of confirming that the needle has successfully penetrated theballoon is to provide means for sensing the pressure of fluid in theballoon, which should detect a pressure drop at the time of penetration.Another possibility is to inject a contrast medium through the needleafter forward movement of the needle has taken place, and confirming itspresence in the balloon by imaging the balloon. Once the needle is inthe balloon, the tag 20 is expelled from the end of the hollow needle bythe pusher 8. This is the stage which is shown in FIG. 2. The purpose ofhaving the optional reticulated sheath 22 is to provide something whichwill catch the tag in the event that the needle 5, instead of enteringthe interior of the balloon 16, ends up adjacent the exterior of itsside wall. The needle is then withdrawn into the sheath 7, which itselfis then withdrawn into the biopsy channel 4 of the endoscope 3.

The balloon catheter is then withdrawn along the same path as that alongwhich it was introduced. In so doing it pulls the tag 20 with it, andthat in turn pulls the thread 21 behind it. Eventually a point isreached where the balloon 16, with the tag 20 therein, emerges throughthe mouth of the patient, at which point the tag, can, if desired, becut off. The ultrasound endoscope is then withdrawn from the patientalso. At this point a situation has been reached where there is a loopof thread which passes in through the mouth of the patient, through theadjacent portions of the stomach wall and small bowel into the interiorof the small bowel, back into the stomach via the pylorus, and thenceonce more out through the patient's mouth. It may be convenient for oneor both end portions of the thread to be distinctively coloured, so thatthe surgeon can be sure as to which end is which.

It is now possible to form an anastomosis using, for example, a deviceof the type described above in which there are two mushroom-shapedbuttons. To assist understanding of the process, an anastomosis buttondevice is shown diagrammatically in FIG. 9. This comprises a pair ofbuttons 130, 131 each having a central aperture 132, 133 respectively,with a pin 134 passing through both apertures. The pin has a head 135,and a compression spring 136 bears between the head 135 and the adjacentbutton 130. For ease of illustration the buttons 130 and 131 are shownspaced apart, but it is to be understood that, in the configurationshown in FIG. 9, the spring 136 would in fact force them together. Theportion of the pin 134 remote from the head 135 has circular ratchetteeth 137 formed thereon. A U-shaped pawl 138 is mounted in the button131, and the base of the is the portion which is visible in theillustration of FIG. 9. The arms of the extend past opposite sides ofthe portion of the pin which is provided with the ratchet teeth 137, andthe arms, being formed of a resilient material, e.g. of metal, bearagainst the ratchet teeth and engage them.

To enable the device of FIG. 9 to be used to form an anastomosis underthe circumstances described above, the button 131 is detached and theremainder of the device is attached to the thread end which leads viathe pylorus to the small bowel. The surgeon then pulls on the otherthread end, which causes the anastomosis-forming device to be drawn inthrough the patient's mouth and eventually to the small bowel side ofthe site where the anastomosis is to be formed. Continued pulling on thethread causes the ratchet-containing portion of the pin 134 to passthrough the adjacent wall portions 1 and 2, so as to protrude into thestomach. The button 131 is then threaded onto the other thread portionextending from the patient's mouth, that thread portion being passedthrough the aperture 133. The button 131 is then caused to slide downthe thread, for example by using a conventional endoscope, with thethread passing up a channel in the endoscope. When the button 131reaches the protruding portion of the pin 134, continued pushing on theintroducing device (e.g. endoscope) pushes the button 131 onto the pin134, causing the pawl 138 to engage with the ratchet teeth. Assumingthat the device for introducing the button 131 is an endoscope, theviewing optics with which it is provided can be used to enable thesurgeon to ensure alignment between the button 131 and the end of thepin 134. The anastomosis device of FIG. 9 is therefore now, in effect,reassembled at the anastomosis site, and the buttons 130 and 131 canexert a force on the tissue between them to produce an anastomosis. Thisis as described in the above-referenced paper by Swain and Mills.

It is to be understood that instead of using buttons of the typedescribed above, other devices could be used to apply the requisitecompression to the tissue, for example one could use an appropriatelymodified prior art magnetic device.

One possible modification to the procedure described above would be touse the ultrasound endoscope to introduce the balloon catheter as wellas the tag, with the ultrasound endoscope being kept in the stomachduring both introductions.

The method described above with reference to FIGS. 1, 1 a, 1 b and 2assumes that it is possible to gain access to both sides of theanastomosis site. Sometimes, however, this will not be possible. Forexample, if, in the condition illustrated in FIG. 8, the tumourcompletely blocked the small bowel the anastomosis site would only beaccessible from the stomach side. Also, one of the organs involved inthe anastomosis may be one which, even in its normal condition, is notaccessible to a catheter, for example the gallbladder. One way ofaddressing this problem is by means of the embodiment shown in FIGS. 3a, 3 b and 4 a to 4 e.

Turning first to FIG. 3 a, this illustrates a situation which has beenreached by using an endoscope to insert a tag 20, with its thread 21,using an endoscope which is the same as, or similar to, the endoscope 3shown in the previous embodiment. The pusher 8 is then withdrawn fromits channel and a guide wire is passed from the patient's mouth, throughthe channel previously occupied by the pusher, and through the hollowneedle 5, into the small bowel. The hollow needle is then withdrawn,leaving the guidewire in place. An elongate member in the form of acatheter 31 is slid down over the guide wire 30 until it reaches theillustrated position. The tip 31 a of the catheter 31 is preferablyformed of a material with relatively low friction (it may, for example,be made of a metal such as stainless steel), so as to make it easier tointroduce the catheter. A thread 32 runs down inside the catheter 31,emerges from the tip 31 a, and has its leading end passing through anaperture 32 b in the body of the catheter, and secured to the body at 32a.

An anastomosis is then formed as follow. Firstly, the guide wire ispreferably withdrawn at least sufficiently so that its tip no longerprotrudes from the end of the catheter. Then the surgeon exerts anupward force on the portion of the thread 32 emerging from the patient'smouth. This causes the distal portion of the catheter 31 to form a loop,as indicated by reference numeral 31 b in FIG. 3 b. As an alternative towhat is described, the thread 32 could run downside the catheter as faras aperture 32 b emerge from the inside of the catheter through theaperture 32 b, and be secured to the catheter at or adjacent the tip 31a. Such a thread would form a loop in the same way as that shown inFIGS. 3 a and 3 b.

The following stages of the procedure are shown with reference to FIGS.4 a to 4 e, and involve the use of a bell-shaped member 40 which,because it acts like one of the buttons 30, 31 in FIG. 9, will bereferred to below as a bell-shaped button. The button 40 isapproximately elliptical as viewed in longitudinal section, as can beseen in FIG. 4 e, and it is the major access of the ellipse which can beseen in each of FIGS. 4 b, 4 c and 4 d.

As indicated in FIG. 4 a, an upward force is exerted by the surgeon onthe catheter 31, so that the loop 31 b urges the tissue portions 1 and 2upwardly at the site intended for the anastomosis. The bell-shapedbutton 40 has a central aperture, and this enables it to be passed downover the catheter 31 to the anastomosis site, as shown in FIG. 4 b.Further downward movement of the bell-shaped button 40 brings it to theposition shown in FIG. 4 c, at which the tissue portions 1 and 2 arecompressed between the button 40 and the loop 31 b. As shown in FIG. 4 c(and in FIG. 4 b) the button 40 carries a compression spring 41. Thiscorresponds in function to the spring 136 in FIG. 9. Thus, the lower endof the spring bears against the button 40 and the upper end of thespring bears against a locking member 42 mounted on the distal end of anupper tubular member 44. The member 42 has an internal pawl engaging aratchet tooth member 43 which faces outwardly from the exterior surfaceof the catheter 31. FIG. 4 c also shows release mechanisms 45 and 46which respectively releasably connect the catheter 31 to a continuationthereof, in a direction towards the patient's mouth, and releasablyconnect the tubular member 44 to a continuation thereof (though inpractice release mechanism 46 may be unnecessary). The nature of theserelease mechanisms is described below with reference to FIGS. 7 a and 7b. In effect, the loop 31 b provides a second button to complement thebutton 40. As with conventional anastomosis buttons, the effect iseventually as shown in FIG. 4 d, with the tissue portions 1 and 2 beingjoined together, and an opening being formed where they were undercompression. The catheter 31 can then be withdrawn, carrying the button40 with it.

In a modification of the embodiment shown in FIGS. 3 a, 3 b and 4 a-4 e,the dome-shaped button 40 could be replaced by a hollow member of someother shape, e.g. ogival. Also, instead of being rigid it could be of aflexible material, preferably an elastic material.

FIGS. 5 a and 5 b show a modification of the catheter 31 used in thepreceding embodiment. In this modification the catheter is provided witha locking tip 47 which is adapted to engage with a complementarystructure in the wall of the catheter when the loop 31 b is formed. Thisavoids the need to maintain tension on the thread 32 to maintain theloop 31 b.

An alternative to the locking mechanism shown in FIGS. 5 a and 5 b wouldbe to insert a locking member, which might, for example, be conical inshape, within the catheter, above where the catheter of FIGS. 5 a and 5b has a locking tip, to clamp the thread 32 against the internal wall ofthe catheter.

FIG. 6 shows an alternative device for forming an anastomosis. This toois capable of being used when there is access to only one side of theanastomosis site. Its operation assumes that a tag 20, with its thread21, has previously been introduced as described with reference to FIGS.1 and 2, or by some similar method. In the condition illustrated in FIG.6 the hollow needle has been withdrawn from the endoscope, but theendoscope is still in position. The method illustrated in FIG. 6 alsoassumes that a guide wire has been provided, the wire being denoted inFIG. 6 by reference numeral 50. This wire is put in position by the sameprocedure as described above with reference to FIGS. 3 a and 3 b, sothat it runs down the biopsy channel 4 of the endoscope, through thetissue portions 1 and 2, beside the thread 21, and terminates on theremote side of the anastomosis site. Preferably the guide wire 50 has asoft tip, and increases in stiffness in a direction away from the tip.

A flexible plastic catheter 51 is passed down the biopsy channel, overthe guide wire 50, until its tip 52 is positioned as shown in FIG. 6.The tip is preferably made of a low friction material, for examplestainless steel. The distal portion of the catheter 51 carries aplurality of flaps 53 which are positioned on the exterior of thecatheter. The flaps 53 may be realised as distinct members (as shown),or they may be formed integrally with the catheter 51. While thecatheter is being pushed down the biopsy tube the flaps 53 lieapproximately parallel to the catheter, but when they emerge on theremote side of the tissue portion 2 they spring outwards to assume thepositions shown in FIG. 6. Preferably there are four such spring flaps,two being located as illustrated, and two further flaps being positionedat 90° to the illustrated flaps, i.e. they extend respectively into andout of the plane of the paper. A second flap-carrying member, in theform of a tube 57 is slid down over the catheter 51 until its springflaps 55 come to bear against the proximal side of the tissue portion 1.As in the case of flaps 53, the flaps 53 may be realised as distinctmembers, or they may be formed integrally with the catheter 51. Theflaps 55 are urged against the tissue portion 1, so causing tissue to becompressed between the flaps 53 and 55, by a spring 56, the lower end ofwhich bears against the upper end of the tube 57, and the upper end ofwhich bears against a pawl member 59. The catheter 51 carries a ratchettooth member 58 (or has teeth formed thereon), of similar constructionto the member 43 described above, and this is engaged by an internalpawl in the pawl member 59 at the lower end of a tubular member 60,thereby to maintain the above compression. The upper part of the deviceof FIG. 6 is surrounded by a catheter 61.

The spring flaps 53 and 55 thus perform the compression function which,in the first of the illustrated embodiments, is performed by the buttons30 and 31, and result in an anastomosis being formed.

FIG. 6 indicates the presence of a release mechanism 80, and an exampleof this is shown in more detail in FIGS. 7 a and 7 b. (FIG. 6 also showsa similar release member 90 in the tubular member 60, though in practicethis may be unnecessary. Indeed its presence may actually make releasemore difficult to achieve, in which case it is preferably omitted). Asshown in FIGS. 7 a and 7 b, the catheter 51 has a main upper portion 51a connected to a lower portion 51 b by the release mechanism 80. In theillustrated embodiment this is formed by a dovetail joint, with onedovetail member 80 a being connected to the main catheter portion, andthe complementary dovetail portion 80 b being connected to the lowercatheter portion 51 b. In the drawing, the portion 80 a is shown asbeing a female member, and the portion 80 b is shown as being a malemember, but of course these could be reversed. The portions 80 a and 80b engage one another quite loosely, but are unable to separate from oneanother as long as the guide wire 50 is in position, as it is in FIG. 7a. The guide wire passes through an aperture in the centre of themembers 80 a and 80 b. However, when the guide wire is withdrawn to theextent shown in FIG. 7 b the members 80 a and 80 b are free to separatefrom one another, and since they are only loosely connected they will doso of their own accord. It is then possible for the surgeon to withdrawthe upper portion of the catheter, with the guide wire, completely fromthe patient, leaving the lower portion in position and passing throughthe anastomosis site. The lower portion can thus then act as a stent tohelp keep the anastomosis open and ensuring drainage. It should be notedthat instead of dovetail members the interlocking portions could be ofany other shape which prevented them from being separated in theposition of FIG. 7 a but permitted them to be separated in the positionof FIG. 7 b. Also, an alternative construction can be envisaged inwhich, instead of keeping the portions 80 a and 80 b together by a guidewire, they could be kept together by an external catheter.

In a modification of the embodiment shown in FIG. 6 the spring flaps 55,but not the spring flaps 53, are replaced by a single conical memberwhich, like the flaps 55 in FIG. 6, is urged against the tissue portion1 by a spring.

A number of further modifications can be made to various devicesdescribed above. One of these is illustrated in FIG. 10, which shows amodified tag 120 which is made of a hollow cylinder of resilientmaterial, and which has split end portions 121 which, when no force isapplied to the tag, adopt the positions shown in FIG. 10. The thread 122is attached to the tag 120 by passing the end through an aperturetherein and tying a knot 123 in the end of the thread. Alternatively,the thread 122 could be crimped in place. When the tag 120 is inside thehollow needle the end portions 121 are urged together by the interiorsurface of the needle. This creates a frictional force between the tagand the needle which helps to ensure that it cannot accidentally fallout of the needle. To eject the tag from the needle requires the pusherto exert a force on the tag sufficient to overcome the frictional force.

If desired, the needle tip, tag, thread and anastomosis button (or theequivalent of those buttons) may be roughened in order to improve theextent to which they reflect ultrasound. Of course, these componentscannot be made too rough, or there may be difficulty in inserting and/orremoving them and, possibly, injury to the patient. It may be desired touse X-ray imaging, preferably in real time, to supplement or replacesome of the other imaging techniques referred to above. In that case itmay be desirable to improve the visibility to X-rays of components, suchas plastic catheters, by marking them, at the tip or elsewhere, with aheavy metal coating.

Another modification, which may be employed where the tag is left inplace during the formation of the anastomosis (e.g. as in the methods ofFIGS. 3 a to 6) is to make the tag of an absorbable material. This maybe useful where the hollow structure within which it is located is onewhich is not externally accessible, for example the gallbladder.Although the tag should be capable of being removed at the end of theprocedure, it may not be, for example if an anastomosis fails to form,and a metal tag remaining in the gallbladder could be a nidus forinfection or stone formation.

Yet another modification in relation to the tag is for it to be ofspiral or angulated shape, enabling it to spread the load exerted by thetag on the tissue portion 2.

It is also noted that the tag, instead of being a completely separateentity mounted in the needle tip, could itself constitute a detachableneedle tip (with a thread attached thereto).

Another possibility in relation to the use of tags is to arrange for aplurality of tags to be dispensed successively from a hollow needle intothe second hollow structure. Such a plurality of tag's might then beused to form one side of the anastomosis device, i.e. replace the buttonor the like on that side of the anastomosis site.

One modification as regards the pusher is that, provided its tip wereappropriate, it could be used as a guide wire, once it has fulfilled itsfunction as a pusher, eliminating the need for a separate guide wire atthat stage at the location where the pusher was able to provide it.

FIGS. 11 and 12 show, in two variants, a particular form of anastomosisdevice which may be used. The device shown in FIG. 11 comprises a firstelement 210 which comprises a carrier member, in the form of a catheter211, which runs through a braided sheath 212. Such sheaths may be of adesign similar to, or the same as, braided sheaths which are used inelectrical work, provided, of course, that the material of the sheath issurgically acceptable. At one of its ends the sheath 212 is fixed to thecatheter 211 by a fixing element 213. The other end of the sheath isattached to a collar 214 which is slidable on the catheter 211. Ratchetteeth 217 are formed on the exterior of a portion of the catheter 211,for a purpose described below.

The device further comprises a second element in the form of an invertedcup 220, the cup having an aperture 22 i in the base thereof, theaperture being large enough to permit the catheter to move through it.

In use the element 220 is positioned on one side of two layers of tissue230, 231, between which the anastomosis is to be formed. A hole 232 haspreviously been formed through the two layers, and one end of thecatheter 211 passes through this hole, through the aperture 221 in thecup 220, and up inside a hollow member 216 (for example the distal endof an endoscope). The remainder of the element 210 is on the oppositeside of the tissue layers.

To form the anastomosis the catheter 211 is drawn upwardly (as viewed inthe drawing), while the cup 220 is pushed downwards by the tubularmember 216, thus drawing the fixing element 213 upwardly, and, with it,the lower end of the sheath 212. This action causes the sheath to bulgeoutwardly, thus bringing the tissue layers 230, 231 into conformity withthe interior surface of the cup 220. Simultaneously, the ratchet teeth217 engage with the periphery of the aperture 221. The teeth permit thecatheter ro move upwardly through the aperture 221 and prevent movementin the opposite direction. The tissue layers are thus compressed betweenthe cup and the sheath. The pressure is maintained long enough for ananastomosis to be formed, after which the device can be removed.

Various modifications can be made to the structure described above. Forexample, the cup may be reduced to a skeletal form 320, as indicated inFIG. 12, where it is shown as consisting of ribs 321, whose upper endsdefine an aperture 322, and a ring 323 connecting the lower ends of theribs. FIG. 12 shows the tissue layer 230 in contact only with the ring(the layers 230 and 231 do not enter the interior of the cup 230). It isto be noted that in the case of cup 220 this too could operate by havingonly the lower rim of the cup in contact with the tissue layer 230, withthe layers 230 and 231 not entering the interior of the cup.

1. A method of forming an anastomosis joining a first tissue layerforming a wall of a first hollow region and a second tissue layerforming a wall of a second hollow region, comprising the steps of:passing a tag from the first hollow region to the second hollow regionthrough the first and second tissue layers, without requiring creationof an external opening, the tag having a trailing portion extending intothe first hollow region, pulling the trailing portion to draw the tissuelayers towards one another and into face-to-face relationship with oneanother, introducing a first component of an anastomosis-forming articleinto the first hollow region, and a second component of ananastomosis-forming article into the second hollow region, the secondcomponent of said article being introduced into the second hollow regionthrough the first and second tissue layers, and after introducing thefirst and second components of the anastomosis-forming article, movingthe first and second components towards one another to compress thefirst and second tissue layers therebetween, and cause the tissue layersto be welded to one another by a consequent ischemia, so as to form ananastomosis communicating the first and second hollow regions.
 2. Amethod according to claim 1, wherein the tag is removably carried by thestep of passing a tag from the first hollow region to the second hollowregion by passing a needle from the first region to the second region bypenetrating said tissue layers.
 3. A method according to claim 1,wherein the step of introducing the said second component into thesecond hollow region comprises providing an elongate member having aproximal region and a distal region terminating in a distal end,inserting the distal region of the elongate member into the secondhollow region in parallel with the trailing portion of the tag, andforming the distal region into a loop, the loop being adapted to act asthe said second component.
 4. A method according to claim 3, wherein thesaid elongate member is hollow, and wherein the loop is formed using athread which runs within the elongate member from the proximal region tothe distal region, emerges from the elongate member at the distal endthereof, and runs externally of the elongate member to a location in thedistal region of the elongate member where it is secured to the elongatemember.
 5. A method according to claim 3, wherein the second componentof the anastomosis-forming article is a hollow member, open in adirection towards the first component thereof.
 6. A method according toclaim 3, wherein the distal end of the elongate member is provided witha locking tip, and the locking tip engages the wall of the elongatemember when the loop is formed.
 7. A method according to claim 1,wherein the step of introducing the said first component into the firsthollow region and the second component into the second hollow regioncomprises providing first and second elongate coaxial members,longitudinally movable with respect to one another, passing the firstelongate member from the first hollow region into the second hollowregion, the said first elongate member having wall-engaging means forengaging the wall of the second hollow region to prevent its return tothe first hollow region, keeping the second elongate member in the firsthollow region, the second elongate member being provided withwall-engaging means to prevent it passing into the second hollow region,the wall-engaging means of the first and second members constitutingrespectively the said second and first components of theanastomosis-forming article.
 8. A method according to claim 7, whereinthe said first elongate member runs within the second elongate member.9. A method according to claim 7, wherein the first elongate member isreleasably attached to an introducing article prior to the introductionof the members into the respective hollow regions, and is detachedthereafter from the introducing article.
 10. A method according to claim9, wherein the said first elongate member is releasably attached to theintroducing article by interengaging portions on a proximal end of thefirst elongate member and a distal end of the introducing article,engagement of the interengaging portions being maintained only while awire passes longitudinally through them or a tube passes longitudinallyaround them.
 11. A method according to claim 1, wherein the said firstcomponent is a hollow member in the form of a cup comprising a base endand an open end, the open end being open in a direction towards the saidsecond component, and the said second component comprising a sheath,wherein the sheath is moved between an extended position in which itsdiameter is sufficiently small for it to pass from the first hollowregion to the second hollow region, and a contracted position in whichits diameter is sufficiently large to prevent it returning from thesecond hollow region to the first hollow region.
 12. A method accordingto claim 11, wherein the sheath is a braided sheath.